Rapid determination of tissue abnormality in pathology is a critical step in the diagnosis of the type and cause of illnesses. Cancers, auto-immune diseases, and bacterial infections have distinct origins but can have similar modes of expression on the tissue level. Detection of biomarkers is critical in accurately diagnosing etiology and establishing proper patient managements. ProteiGene and collaborators at Harvard Medical School/Massachusetts General Hospital propose to develop MALDI-ToF mass spectrometry as a diagnostic tool for analyzing fluid aspirations of pleural effusions and pancreatic cysts to determine etiologies of the disorder. These common conditions indicate the possible presence of infection, malignancy, heart disease, or inflammation. Established methods are unable to diagnose the conditions properly in a large fraction of the cases. MALDI-ToF mass spectrometry is a sensitive technique for analyzing whole cells. It requires little preparation and is known to detect specific biomarkers that may be indicative of the causes of the lung or pancreatic conditions. PROPOSED COMMERCIAL APPLICATION ProteiGene, Inc. is a mass spectrometry applications company. ProteiGene collaborates with partners in the health care, agriculture, public health and food industries to provide diagnostic techniques for rapid, accurate identification of disease state, infection and/or biocontamination. The ideas proposed here would lead to the development of diagnostic equipment that would complement existing techniques in hospital pathology laboratories.